I use Transmission on Ubuntu and I'm having this issue, which basically says that QoS is broken because there is no way to limit which outgoing ports uses. I was thinking of doing a dirty and ugly hack and create an interface alias and define QoS based on source address, but was wondering if is there another way. Is it possible to mark the packets on the original machine in some way, using the owner and mark modules of iptables and sending this to the router who does the QoS? From what I understand, mark on iptables only applies to the local machine, so this will not work, but is there another way?